Add error messaging for x509 commit signing problems
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Currently if an x509 certificate used to sign a commit is in some way deficient, such as missing `crlDistributionPoints` or the like, then no error is raised and instead there's just a rather cryptically missing `Verified`/`Unverified` badge.
If there is an issue with the certificate we should most likely generate a log message, and also consider an `Error` badge with details of the error in place of the `Verified`/`Unverified` badge.
Related https://gitlab.com/gitlab-org/gitlab/-/issues/295297
Related https://gitlab.com/gitlab-org/gitlab/-/issues/293697
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